I built a free JSON formatter that works 100% offline — because I was tired of pasting secrets into random websites

Mubashir Ahmad — Sat, 14 Mar 2026 10:58:20 +0000

Every developer has done this.

You grab a JSON response from your API, paste it into some random online formatter,
and suddenly realize — wait, that had my database credentials in it.

That moment of panic is why I built this tool.

What I Built

A completely free, 100% offline JSON formatter, validator, and auto-repair tool.

👉 https://secure-json-repair.netlify.app/

No server. No database. No tracking. Zero network requests when you use it.
You can literally turn off your WiFi and it still works perfectly.

Features

Format & Beautify
Paste messy JSON and instantly get clean, indented, readable output.
Choose between 2 spaces, 4 spaces, or tabs.

Auto-Repair
This is my favourite feature. Most tools just say "your JSON is invalid."
This tool actually fixes it. It automatically cleans up:

Trailing commas (the #1 JSON mistake)
Single-quoted strings
Unquoted keys
JavaScript comments

Collapsible Tree View
Explore deeply nested JSON by collapsing and expanding nodes.
Hover over any key to copy its exact dot-notation path like
users[0].address.city — super useful for writing queries.

Sort Keys A→Z
Recursively sort all object keys alphabetically with one click.
Great for comparing API responses.

Light & Dark Mode
Respects your system preference. Saves your choice locally.

Syntax Highlighting
One Dark Pro inspired theme with JetBrains Mono font.
Feels like VS Code in a browser tab.

Why I Care About This

I work with APIs every day. JSON is everywhere.
And almost every online JSON tool I found either:

Sends your data to a server
Shows you ads
Looks like it was built in 2009
Just tells you the JSON is broken without helping you fix it

I wanted something that felt like a proper developer tool.
Clean, fast, private, and actually helpful when things go wrong.

Tech Stack

Just vanilla HTML, CSS, and JavaScript.
No frameworks. No dependencies. No build step.
One single HTML file you could save to your desktop and use forever.

Try It